In general, a fuel evaporation gas vaporizing from a gasoline fuel which is used as the fuel of a vehicle internal combustion engine may easily combust when it is exposed to static electricity or spark. A gasoline evaporation gas may be present inside of a fuel tank and a fuel injection tube since a gasoline fuel fluctuates in a fuel tank, causing the fuel to vaporize, when it is a high temperature or while a vehicle drives.
Since the fuel evaporation gas has a high flammability, even a small flame may react with surrounding oxygen and may combust like an explosion, for which the engine of a vehicle should be shut off during the fueling in order to keep away from any flame causing elements. Despite the above facts, there may be a fire due to the explosion of a gasoline gas inside of a fuel injection hole due to a static electricity or a spark which may occur in the middle of opening a fuel injection hole cap when lubricating a vehicle.
In order to prevent any explosion of a fuel evaporation gas due to a static electricity, the Korean Patent Publication No. 10-2006-0040955 (the title of the invention: fuel injection hole structure for preventing fire) describes that since a gasoline gas (fuel evaporation gas) present inside of a fuel injection hole in the middle of opening a fuel injection hole cap of a vehicle automatically emits to the outside of the fuel injection hole, it is possible to prevent any explosion of a gasoline gas due to a static electricity or a spark and any fire due to the explosion which may occur in the middle of opening a fuel injection hole cap.
FIG. 1 is a view illustrating a prior art. In a fuel injection hole structure for a vehicle which is opened or closed by a fuel injection hole cap 10, an auxiliary cap 14 with a diameter similar with the diameter of a fuel injection hole 12 is connected using a vertical bar 16 to the bottom of the fuel injection hole cap 10, and a plurality of discharge ports 20 are formed at an inner diameter surface of the fuel injection hole 12, and two rows of opening and closing plates 18 which are opened due to the ascending and descending operations of the auxiliary cap 14 are engaged to the discharge port 20. For the sake of fueling, when rotating open the fuel injection hole cap 10, the surrounding surface of the auxiliary rap 14 pushes in sequence the two upper and lower rows of the opening and closing plates 18, and at the same time the bottoms of the two upper and lower rows of the opening and closing plates 18 are opened in sequence about the rotation point of a hinge spring 22. The two upper and lower rows of the discharge ports 20 are opened toward the outside, so the gasoline gas present inside of the fuel injection hole 12 may easily emit through the two upper and lower rows of the discharge ports 20, thus preventing any explosion and fire even when a static electricity or a spark occurs.
However, the above prior art is directed to a way of previously removing to the outside the fuel evaporation gas present inside of the fuel tank when opening the fuel injection hole cap; however if a spark occurs by a static electricity when a user opens the fuel injection hole cap, the emitting fuel evaporation gas may be ignited, which may cause fire. In addition, if the fuel tank is filled full, fuel may leak through a discharge port 20 dedicated to the emission of the fuel evaporation gas (gasoline gas).
Given the above mentioned problems, as illustrated in FIG. 2, the users who try to previously prevent any occurrence of such static electricity always carry a static electricity discharge device (static electricity discharger) formed in a shape of a portable key ring (discharger made of diode, neon light or fiber with high conductivity) with them and use them when lubricating.
The conventional vehicle static electricity discharge device designed for the above-mentioned purposes is made in a portable key ring shape wherein the components of static electricity discharge devices may be directly provided at a vehicle key, etc. or as illustrated in FIG. 2, the static electricity discharge device 30 may be made in a shape of a portable decoration item. When a user touches a static electricity discharge circuit contact unit 31 made of a metallic material with a metallic conductive portion of an electronic appliance, a vehicle, etc., the static electricity accumulated in the body flows through the static electricity discharge circuit contact unit 31—a conductive wire 33—a metallic conductive unit 32—a vehicle body (metallic conductive material) and to the ground, thus discharging. At this time, the diode 34 or the neon light designed for the user to check out whether or not the static electricity is discharged may be provided at an intermediate portion of the conductive wire 33, so when the static electricity flows to the ground, the diode 34 may turned on/off, generating flash, which helps the user to check that it is safe to use.
Since the portable static electricity prevention device in general is kept in a user's pocket of a clothes or in a handbag and is taken out when in use, the user should always be aware of the discharge of the static electricity, otherwise, it is hard for the user to use such a device by taking out for each situation. Once the user forgets the use of the device, a big disaster may take place because of static electricity. Therefore, the above-described conventional device is not enough to be used for the sake of a reliable static electricity prevention means.